/*
 * Copyright 1999-2012 Alibaba Group.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
/**
 * (created at 2011-1-23)
 */
package fm.liu.timo.parser.ast.expression.primary.function.groupby;

import java.util.List;
import fm.liu.timo.parser.ast.expression.Expression;
import fm.liu.timo.parser.ast.expression.primary.function.FunctionExpression;
import fm.liu.timo.parser.visitor.Visitor;

/**
 * @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
 */
public class Count extends FunctionExpression {
    /**
     * either {@link distinct} or {@link wildcard} is false. if both are false, expressionList must
     * be size 1
     */
    private final boolean distinct;

    public Count(List<Expression> arguments) {
        super("COUNT", arguments);
        this.distinct = true;
    }

    public Count(Expression arg) {
        super("COUNT", wrapList(arg));
        this.distinct = false;
    }

    public boolean isDistinct() {
        return distinct;
    }

    @Override
    public FunctionExpression constructFunction(List<Expression> arguments) {
        return new Count(arguments);
    }

    @Override
    public void accept(Visitor visitor) {
        visitor.visit(this);
    }
}
